storage: Cleanup class/struct forward declarations

storage/browser/fileapi/file_system_backend.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef STORAGE_BROWSER_FILEAPI_FILE_SYSTEM_BACKEND_H_
 #define STORAGE_BROWSER_FILEAPI_FILE_SYSTEM_BACKEND_H_
 
 #include <stdint.h>
 
 #include <limits>
@@ skipping 13 matching lines @@
 class GURL;
 
 namespace storage {
 
 class AsyncFileUtil;
 class CopyOrMoveFileValidatorFactory;
 class FileSystemURL;
 class FileStreamReader;
 class FileStreamWriter;
 class FileSystemContext;
-class FileSystemFileUtil;
 class FileSystemOperation;
 class FileSystemQuotaUtil;
 class WatcherManager;
 
 // Callback to take GURL.
 typedef base::Callback<void(const GURL& url)> URLCallback;
 
 // Maximum numer of bytes to be read by FileStreamReader classes. Used in
 // FileSystemBackend::CreateFileStreamReader(), when it's not known how many
 // bytes will be fetched in total.
@@ skipping 142 matching lines @@
   // as confirming if a file or a directory exist before granting the final
   // permission to the entry. The path must be an absolute path.
   virtual storage::FileSystemURL CreateInternalURL(
       storage::FileSystemContext* context,
       const base::FilePath& entry_path) const = 0;
 };
 
 }  // namespace storage
 
 #endif  // STORAGE_BROWSER_FILEAPI_FILE_SYSTEM_BACKEND_H_